Two airborne campaigns were carried out to measure the tropospheric concentrations and variability of CO2, CO and O3 over Siberia. In order to quantify the influence of remote and regional natural and anthropogenic sources, we analysed a total of 52 vertical profiles of these species collected in April and September 2006, every ∼200 km and up to 7 km altitude. CO2 and CO concentrations were high in April 2006 (respectively 385–390 ppm CO2 and 160–200 ppb CO) compared to background values. CO concentrations up to 220 ppb were recorded above 3.5 km over eastern Siberia, with enhancements in 500–1000 m thick layers. The presence of CO enriched air masses resulted from a quick frontal uplift of a polluted air mass exposed to northern China anthropogenic emissions and to fire emissions in northern Mongolia. A dominant Asian origin for CO above 4 km (71.0%) contrasted with a dominant European origin below this altitude (70.9%) was deduced both from a transport model analysis, and from the contrasted ΔCO/ΔCO2 ratio vertical distribution. In September 2006, a significant O3 depletion (∼–30 ppb) was repeatedly observed in the boundary layer, as diagnosed from virtual potential temperature profiles and CO2 gradients, compared to the free troposphere aloft, suggestive of a strong O3 deposition over Siberian forests.

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We analyse data from weekly rocket temperature soundings up to 75 km carried out since mid‐1960s at polar (Heiss Island, 80.6°N and Molodezhnaya, 67.7°S), temperate (Volgograd, 48.7°N and Balkhash, 46.8°N) and tropical (Thumba, 8.5°N) latitudes. All records show significant cooling which is of the order of a few degrees K at 30–40 km, 10 K at 50 km and 20 K at 60–70 km. In the mesosphere the temperature trends are estimated from the hydroxyl rotational temperature records which start in 1957 at Zvenigorod (55.7°N) and Abastumani (41.8°N). These are related to the mesopause at 87 km and also show a cooling of about 30 K during the time. The cooling is qualitatively consistent with increasing concentration of greenhouse gases but may also reflect the changing chemistry of stratosphere and mesosphere, which is clearly seen in increasing emission intensities of hydroxyl during the last decades. Therefore the stratosphere and mesosphere may be regions with the strongest signals of global change.

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